Conventionally, for example, there is a technique in which apparatuses communicate with each other using near field communication such as NFC (Near Field Communication). In near field communication, in accordance with the fact that a communication target has approached an initiator-side near field communication apparatus, the communication target is identified on the near field communication apparatus side, and communication is started. For example, in conventional near field communication, to detect whether or not a communication target has approached the range where communication can be performed, an initiator-side near field communication apparatus performs polling. Then, if the approach of a communication target to the range where communication can be performed has been detected, near field communication is performed between the initiator-side near field communication apparatus and the communication target.
When performing the above polling, the initiator-side near field communication apparatus may periodically send out a radio wave (a polling signal) for confirming the presence of a communication target. Then, if a communication target has approached the near field communication apparatus, an influence appears also in the near field communication apparatus by the coil inductive coupling between the near field communication apparatus and the communication target. Then, this influence is detected, thereby detecting the approach of the communication target. For example, the above influence appears as a result of changes in the amplitude and the phase of the antenna voltage of the near field communication apparatus side that are caused by a change in the impedance of the communication target by the sent polling signal.
The above influence is caused also when an object other than a communication target, such as metal or an antenna of another apparatus, has approached the initiator-side near field communication apparatus. Thus, after the approach of a communication target to the range where communication can be performed has been detected, if the initiator-side near field communication apparatus cannot start near field communication with the communication target, the initiator-side near field communication apparatus determines that the detected communication target is an object other than a target of near field communication. Then, the initiator-side near field communication apparatus performs control so that the communication target is not to be detected. For example, if the approach of an object other than the above target has been erroneously detected, the initiator-side near field communication apparatus excludes from detection targets an influence having appeared in the above detection (for example, excludes, from detection targets, changes in the amplitude and the phase of the antenna voltage that have appeared as the above influence), thereby preventing erroneous detection in the subsequent processing.
However, when a communication target is a device capable of turning on or off an NFC card emulator function, if the card emulator function has been turned on after the device had been brought into proximity to the initiator-side near field communication apparatus and the above erroneous detection prevention function had worked, the device may be excluded from communication targets.
Therefore, it is an object of an exemplary embodiment to provide a communication system, a communication terminal apparatus, and a communication method that are capable of avoiding the situation where communication becomes difficult in wireless communication performed by devices coming into proximity to each other, and a storage medium having stored therein a communication program capable of avoiding the situation where communication becomes difficult in wireless communication performed by devices coming into proximity to each other.
To achieve the above object, the exemplary embodiment can employ, for example, the following configurations. It should be noted that it is understood that, to interpret the descriptions of the claims, the scope of the claims should be interpreted only by the descriptions of the claims. If there is a conflict between the descriptions of the claims and the descriptions of the specification, the descriptions of the claims take precedence.
An exemplary configuration of a communication system according to an exemplary embodiment is a communication system including an information processing apparatus and a communication terminal apparatus for performing wireless communication with the information processing apparatus while being in proximity to the information processing apparatus. The information processing apparatus includes a communication target sensor and an initiator-side data transceiver. The communication target sensor, via an antenna of the information processing apparatus, sends out a radio wave for confirming presence of a communication target near the antenna, and senses a change in a magnetic field caused by coil inductive coupling between the antenna and another antenna, thereby sensing the presence of the communication target. The initiator-side data transceiver, if the presence of the communication target has been confirmed near the antenna of the information processing apparatus, performs data communication with the communication target. The communication terminal apparatus includes an antenna controller and a target-side data transceiver. The antenna controller, before data communication is performed with the information processing apparatus via an antenna of the communication terminal apparatus, changes at least one of a resistive component of the antenna, voltage to be applied to the antenna, and current to be applied to the antenna, thereby changing a state of the antenna to cause a change in the magnetic field that results from the change in the state of the antenna and can be sensed by the communication target sensor. The target-side data transceiver, after the antenna controller has changed the state of the antenna, performs the data communication with the information processing apparatus.
Based on the above, even if a communication terminal apparatus has once been excluded from targets of the detection of a communication target performed by an information processing apparatus, it is possible to disable this exclusion setting by forcibly changing a magnetic field generated by the coil inductive coupling between an antenna of the information processing apparatus and an antenna of the communication terminal apparatus before data communication is performed. This can avoid the situation where wireless communication performed by devices coming into proximity to each other becomes difficult.
Further, in accordance with the fact that the communication terminal apparatus has started emulation that enables the wireless communication, the antenna controller may change the state of the antenna of the communication terminal apparatus.
Based on the above, in accordance with the fact that the emulation of the communication terminal apparatus has been started, the state of the antenna changes. This makes it possible to certainly perform wireless communication using this emulation function.
Further, the antenna controller may reduce the resistive component of the antenna of the communication terminal apparatus before the data communication is performed, thereby changing the state of the antenna of the communication terminal apparatus.
Based on the above, a resistive component of the antenna of the communication terminal apparatus is reduced before the data communication is performed. This makes it possible to easily change the magnetic field generated by the coil inductive coupling between the antenna of the information processing apparatus and the antenna of the communication terminal apparatus.
Further, after the data communication with the information processing apparatus has ended, the antenna controller may increase the resistive component of the antenna of the communication terminal apparatus.
Based on the above, the resistive component of the antenna is small during the data communication. This also makes it possible to perform stable data communication such that the load during the data communication process does not increase. Further, before the start of the next data communication, it is possible to bring the communication terminal apparatus into proximity to the information processing apparatus with the resistive component of the antenna being large.
Further, the antenna controller may temporarily reduce the resistive component of the antenna of the communication terminal apparatus.
Based on the above, the resistive component of the antenna of the communication terminal apparatus is temporarily reduced. This can avoid the situation where wireless communication becomes difficult.
Further, before the data communication is performed, the antenna controller may increase the resistive component of the antenna of the communication terminal apparatus, thereby changing the state of the antenna of the communication terminal apparatus.
Based on the above, a resistive component of the antenna of the communication terminal apparatus is increased before the data communication is performed. This makes it possible to easily change the magnetic field generated by the coil inductive coupling between the antenna of the information processing apparatus and the antenna of the communication terminal apparatus.
Further, if a response has been given by the information processing apparatus through the wireless communication after the resistive component had been increased, the antenna controller may reduce the resistive component of the antenna of the communication terminal apparatus.
Based on the above, the resistive component of the antenna is small during the data communication. This makes it also possible to perform stable data communication such that the load during the data communication process does not increase. Further, before the start of the next data communication, it is possible to bring the communication terminal apparatus into proximity to the information processing apparatus with the resistive component of the antenna being small.
Further, the antenna controller may temporarily increase the resistive component of the antenna of the communication terminal apparatus.
Based on the above, the resistive component of the antenna of the communication terminal apparatus is temporarily increased. This can avoid the situation where wireless communication becomes difficult.
Further, if a response has not been given by the communication target after the presence of the communication target had been confirmed near the antenna of the information processing apparatus, the initiator-side data transceiver may stop the data communication with the communication target. The communication target sensor may exclude, from subsequent sensing targets, a change in the magnetic field caused by the communication target with which the data communication has been stopped, thereby continuing a process of sensing presence of a new communication target.
Based on the above, if an object that is not a communication target of the information processing apparatus has come into proximity, it is possible to eliminate the object from communication targets and continue detecting a communication target.
Further, in accordance with whether or not a change in the magnetic field has been sensed in which an amount of change from a reference magnetic field strength is equal to or greater than a predetermined amount, the communication target sensor may sense the presence of the communication target present near the antenna of the information processing apparatus.
Based on the above, a change in the magnetic field is sensed, whereby it is possible to easily detect a communication target coming into proximity to the information processing apparatus.
Further, the exemplary embodiment may be carried out in the forms of a communication terminal apparatus that can be included in the above communication system, a storage medium having stored therein a communication program for causing a computer to execute at least some of the operations of the above components, a communication method including the operations of the above components, and the like.
According to the exemplary embodiment, even if a communication terminal apparatus has once been excluded from targets of the detection of a communication target performed by an information processing apparatus, it is possible to disable this exclusion setting by forcibly changing a magnetic field generated by the coil inductive coupling between an antenna of the information processing apparatus and an antenna of the communication terminal apparatus before data communication is performed. This can avoid the situation where wireless communication performed by devices coming into proximity to each other becomes difficult.
These and other objects, features, aspects and advantages of the exemplary embodiments will become more apparent from the following detailed description of the exemplary embodiments when taken in conjunction with the accompanying drawings.